PowerBuilder

Download File (Stream to Local Filesystem)

See more Google Drive Examples

This example demonstrates how to download the content of a file from Google Drive. The file is streamed to the local filesystem. PowerBuilder

integer li_rc
long li_Success
oleobject loo_GAuth
oleobject loo_Rest
long li_BAutoReconnect
oleobject loo_GdCache
string ls_FileId
oleobject loo_SbPath
oleobject loo_FileStream
string ls_JsonResponse

li_Success = 0

li_Success = 1

//  It requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  This example uses a previously obtained access token having permission for the 
//  Google Drive scope.

loo_GAuth = create oleobject
li_rc = loo_GAuth.ConnectToNewObject("Chilkat.AuthGoogle")
if li_rc < 0 then
    destroy loo_GAuth
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_GAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"

loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")

//  Connect using TLS.
//  A single REST object, once connected, can be used for many Google Drive REST API calls.
//  The auto-reconnect indicates that if the already-established HTTPS connection is closed,
//  then it will be automatically re-established as needed.
li_BAutoReconnect = 1
li_Success = loo_Rest.Connect("www.googleapis.com",443,1,li_BAutoReconnect)

//  Provide the authentication credentials (i.e. the access token)
loo_Rest.SetAuthGoogle(loo_GAuth)

//  ------------------------------------------------------------------------------
//  To download a file, we must know the file ID.
//  In a previous example (see Build Local Metadata Cache
//  we built a local cache to make it easy to lookup file IDs given a file path.
//  Let's say we want to download "testFolder/abc/123/penguins.jpg".
//  First we lookup the fileId in the cache.  With the fileId, we can download the file.
loo_GdCache = create oleobject
li_rc = loo_GdCache.ConnectToNewObject("Chilkat.Cache")

loo_GdCache.Level = 0
loo_GdCache.AddRoot("C:/ckCache/googleDrive")

ls_FileId = loo_GdCache.FetchText("testFolder/abc/123/penguins.jpg")
if loo_GdCache.LastMethodSuccess <> 1 then
    Write-Debug "Filepath not found in cache."
    destroy loo_GAuth
    destroy loo_Rest
    destroy loo_GdCache
    return
end if

//  We need to send a GET request like this:
//  GET https://www.googleapis.com/drive/v3/files/fileId?alt=media
//  The fileId is part of the path.
loo_SbPath = create oleobject
li_rc = loo_SbPath.ConnectToNewObject("Chilkat.StringBuilder")

loo_SbPath.Append("/drive/v3/files/")
loo_SbPath.Append(ls_FileId)
loo_Rest.AddQueryParam("alt","media")

//  Create a stream object with a SinkFile set to the path where the downloaded file will go.
loo_FileStream = create oleobject
li_rc = loo_FileStream.ConnectToNewObject("Chilkat.Stream")

loo_FileStream.SinkFile = "qa_output/penguins.jpg"
//  Indicate that the response body should stream directly to fileStream,
//  but only if the response status is 200.  
loo_Rest.SetResponseBodyStream(200,1,loo_FileStream)

//  Download the file, streaming the content to the SinkFile.
ls_JsonResponse = loo_Rest.FullRequestNoBody("GET",loo_SbPath.GetAsString())
if loo_Rest.LastMethodSuccess <> 1 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_GAuth
    destroy loo_Rest
    destroy loo_GdCache
    destroy loo_SbPath
    destroy loo_FileStream
    return
end if

//  A successful response will have a status code equal to 200.
if loo_Rest.ResponseStatusCode <> 200 then
    Write-Debug "response status code = " + string(loo_Rest.ResponseStatusCode)
    Write-Debug "response status text = " + loo_Rest.ResponseStatusText
    Write-Debug "response header: " + loo_Rest.ResponseHeader
    destroy loo_GAuth
    destroy loo_Rest
    destroy loo_GdCache
    destroy loo_SbPath
    destroy loo_FileStream
    return
end if

Write-Debug "File downloaded."


destroy loo_GAuth
destroy loo_Rest
destroy loo_GdCache
destroy loo_SbPath
destroy loo_FileStream